Memory Issues on VPS (1 post)

I just purchased VPS hosting recently and transfered my blog over. Since then I have had huge memory consumption. There is nothing in the error_log files and everything looks fine. To be on the safe side I deleted the entire blog, and imported the xml file and set up everything from scratch.

Is all of this normal? I was on shared hosting and server load was a big issue for my site (15K page loads a day) but memory never got over 45%. Now on the VPS (with 740MB ram) I hit 100% memory occasionally (load is fine usually), and hover at 60%-70% very often.